Excavation of trenches for buried walls



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EXCAVATION OF TRENCHES FOR BURIED WALLS 5 Sheets-sh 1 Filed Aug, 2 1967 LO N QxQ

1970 FUKUICHI KUKIHARA 3,509,949 I EXCAVATION 0F TRENCHES FOR BURIED WALLS Filed Aug. 28, 1967 5 Sheets-Sheet 2 FIG. 2

1970 FUKUICHI KUKIHARA 3,509,949

EXCAVATION OF TRENCHES FOR BURIED WALLS Filed Aug. 28, 1967 5 Sheets-Sheet 3 5, l970 FUKUICHI KUKIHARA 3,509,949

EXCAVATION OF TRENCHES FOR BURIED WALLS Filed Aug. 28, 1967 5 Sheets-Sheet 4.

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TI 75 74 f y 1970 FUKUICHI KUKIHARA 3,509,949

EXCAVATION OF TRENCHES' FOR BURIED WALLS Filed Aug. 28, 1967 5 Sheets-Sheet 5 United States Patent 3,509,949 EXCAVATION F TRENCHES' FOR BURIED WALLS Fukuichi Kukihara, Tokyo-to, Japan, assignor to Kabushiki Kaisha Tone Boring, Tokyo-t0, Japan, a jointstock company of Japan Filed Aug. 28, 1967, Ser. No. 663,615 Claims priority, application Japan, Nov. 9, 1966 (utility model), 41/102,977 Int. Cl. E02f 3/88 US. Cl. 175-40 1 Claim ABSTRACT OF THE DISCLOSURE An excavator having a row of several drill bits provided with partly overlapping drilling paths, and in which some bits rotate counter to the others, is freely suspended and lowered as it excavates a trench, with water being forcibly ejected through some of the bits to form mud and thereby facilitate drilling, and the resulting mud being drawn through the other bits for removal.

BACKGROUND OF THE INVENTION This invention relates generally to techniques in forming long narrow excavations in soil and more particularly to a new technique for excavating continuously long narrow excavations (hereinafter referred to as trenches) for placement therein of buried walls such as earth retaining walls, sheathings, and water barrier walls.

For forming trenches in soil for retaining soil or water, it is known in the art to first drill a series of vertical cylindrical holes at constantly spaced intervals and thereafter demolish and remove the walls between these holes to produce a continuous trench.

By this prior method, however, it is extremely difficult, if not impossible, to form trenches of the desired direction, shape, and dimensions in a rapid and efficient manner.

Another method proposed heretofore is to use a row of drill bits at the lower ends of long drill rods driven by driving mechanisms at the ground level. This method, however, imposes excessive stresses on the entire device particularly when trenches without askewness are to be excavated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of and equipment for efficiently forming trenches of the desired directions, shapes, and dimensions in the ground.

Another object of the invention is to prevent the application of abnormal or excessive forces on the equipment parts supporting an excavating machine by suspending the excavating machine assembly in a free state by means of a suspension wire and a wire-rope tackle instead of rigidly supporting the assembly by means of drill rods.

Still another object of the invention is to provide an excavating machine in which its prime mover is mounted directly thereon thereby overcoming the necessity of providing mechanical power transmitting means between the ground level and the excavating machine.

A further object of the invention is to provide an excavating machine having a plurality of drill bits and means for causing some of the drill bits to rotate in a direction opposite to that of the other drill bits thereby preventing undesirable askew turning of the excavating machine by virtue of which the trench would otherwise assume a warped or twisted shape.

A still further object of the invention is to cause a forced circulation of water between the bottom of the trench "ice and the ground level thereby facilitating the excavation operation.

An additional object is to provide a twist detecting device for detecting undesirable twist or askewness in the position of the excavating machine during the excavating operation.

Other objects and advantageous features of the invention will become apparent as the disclosure proceeds.

According to the present invention, briefly summarized, there is provided an excavator for excavating trenches for walls comprising, essentially, an excavator body, a plurality of drill bits rotatably supported in a row at the bottom of the excavator body, adjacent drill bits having partly overlapping drilling paths, and a controllable prime mover mounted on the excavator body for driving the drill bits through a gear mechanism whereby approximately one-half of the bits rotate in a direction opposite to that of the remainder of the bits.

There is further provided in addition to the above described excavator, a hoisting device for controllably positioning the excavator and supporting the excavator in a suspended state during the excavating operation, a control system for controlling the prime mover, a water supply device for supplying water through some of the drill bits to form mud to facilitate drilling, and a mud removal device for removing the mud thus formed through the remainder of the bits.

The nature, principle, details, and utility of the invention will be more clearly apparent from the following detailed description with respect to a preferred embodiment of the invention when read in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a diagrammatic elevational view, partly in vertical section, showing the general organization of one example of excavation equipment according to the invention;

FIG. 2 is an elevational view showing the general organization of an example of an excavating machine or excavator according to the invention for use in the equipment shown in FIG. 1;

FIG. 3 is an elevational view, in vertical section, showing the bit driving shafts and the state of their intercoupling by gears in the main gear casing of the excavating machine;

FIG. 4 is an elevational view, partly in section and with parts cut away, showing the gear train within the reduction gear casing of the prime mover of the excavating machine; and

FIGS. 5 and 6 are respectively a plan view, with a part in section, and an elevational view showing a device for detecting skewness of the excavating machine structure.

Referring to FIG. 1, the excavation equipment illustrated therein is made up essentially of an excavating machine 10 (hereinafter referred to as the excavator 10), a derrick or frame tower 11 for hoisting the excavator 10, a winch 12 for controllably moving the excavator 10 vertically, a cable reel 13 for taking up slack in the power supply cable of the excavator 10, a pump 14 for supplying water to the excavator 10, and a mud treatment machine 15 installed at ground level for drawing mud upwardly through the excavator 10 and separating the solid sediments from water.

A pair of head sheaves 16 is rotatably supported at the top of the tower 11, and one end of a wire rope 17 passed over the sheaves 16 is anchored to a point 18 at the base of the tower 11 through a cylinder device (not shown) for indicating the tension in the wire rope. From the point 18, the wire rope is passed over and around one of the head sheaves 16, under and around the sheave of a running 'block 19, and over and around the other sheave 16 and is then directed to and wound around the drum of the winch 12 mounted on the base of the tower 11.

The excavator 10 is suspended from the running block 19 by a suspension wire 20. Thus, by winding and unwinding the winch 12, the excavator 10 can be raised and lowered, with the vertical stroke of the drills of the excavator 10 being one half of the length of the wire rope 17 either wound or unwound.

The motive power source of the excavator 10, for example, two electric motors, are controllably supplied with power from a control device 22 through a water-tight cable 21 wound around a cable reel 13 provided at the ground level for taking up slack in the cable 21.

Water pumped by the pump 14 is delivered through a flexible hose 23 into the excavator 10. Mud is drawn up through the excavator 10 and through a hose 24 to the mud treatment apparatus 15. This drawing up of the mud is accomplished by the so-called air lift method whereby the mud is lifted by air transmitted from the ground level or by a method depending upon a suction pump installed at ground level, that is, a forced circulation method involving the washing of the bits by supplied water and the mud removal by the drawing up of the mud. The interior of a trench 25 being excavated by the excavator 10 is filled with muddy water.

The details of the excavator 10 are shown in FIG. 2. The excavator is provided with two prime movers 30, which are, for example, vertical electric motors of a watersubmersible construction mounted on a reduction gear casing 31 housing a reduction gear mechanism described hereinafter. Below the casing 31, there is provided a main gear casing 34 for housing the vertical drive shafts of drill bits 32,, 32 32 32, 32 32 and 32 and a gear mechanism for the intercoupling of the bit drive shafts as described hereinafter.

This main gear casing is made of several casing sections 34,,, 34 34 34 34. 34 and 34,; secured together integrally in a row and is connected integrally with the above mentioned reduction gear casing 31 by connecting plates 35. Each of the casing sections 34 through 34 houses a vertical bit drive shaft and is rigidly fixed to the adjacent casing section or sections by bolts and nuts 36.

Throughout the following description, reference numerals with subscripts a through g respectively designate similar parts disposed in or associated with these casing sections 34 through 34 although some of these numerals and their respective parts may be omitted in the drawings for the sake of simplification of the drawings.

Referring to FIG. 3, the bit drive shafts housed within the main gear casing 34 for driving the bits 32 through 32 and designated by reference numeral 44 with corresponding subscripts a through g are rotatably supported by respective pairs of upper and lower bearings. For example, the central shaft 44,, is supported by a pair of bearings 45 A bevel gear is fixed to each bit shaft between its two bearings. For example, a bevel gear 46. is fixed by means such as a key to the central shaft 44 Furthermore, each bit drive shaft is provided around its upper and lower end parts with sealing or packing devices for preventing mud and water from infiltrating into the corresponding casing section. For example, the central shaft 44 is provided with packing devices 47 In addition, each bit drive shaft has a hollow passageway formed therethrough in its axial direction for passage therethrough of a fluid such as water or mud. For example, the central shaft 44 has a passageway 48 In the spaces between adjacent bit driving shafts, there are respectively disposed cross shafts 50 with their axes perpendicular to the axes of the bit drive shafts. Each of the cross shafts 50 are rotatably supported at its middle part by a bearing 51 suitably supported in turn by a structural part of the main gear casing 34. Bevel gears 49 are fixed to the ends of each cross shaft 50 and are in mesh with the bevel gears 46 fixed respectively to the two neighboring bit drive shafts 44. For example, the bevel gears 49 on the ends of the cross shaft between the bit drive shafts 44,, and 44. are respectively in mesh with the bevel gears 46,, and 46 fixed respectively to shafts 44 and 44 Thus, when the central bit drive shaft 44 rotates, all of the bit drive shafts 44 through 44 also rotate. It is to be observed, however, that the bevel gears 46 fixed to the central bit drive shaft 44,, and the bit drive shafts to the left thereof, as viewed in FIG. 3, face upwardly and engage with the lower sides of their respective gears 49 fixed to the cross shafts 50. The bevel gears 46 fixed to the bit drive shafts 44 to the right of the central shaft 44 face downwardly and engage with the upper sides of their respective gears 49.

By reason of these particular relationships between the bevel gears, if the central shaft 44 rotates in the direction of the arrow as indicated in FIG. 2 (i.e., clockwise as viewed from above), the other bit drive shafts will rotate in the directions indicated by their respective arrows. That is, the shafts 44 44 and 44 will rotate in a clockwise direction, and shafts 44,, 44 and 44; in a counterclockwise direction, as viewed from above.

The bit drive shafts are provided at their lower ends with respective shaft coupling flanges 52 to which respective drill bits 32 are fixedly coupled. Each of the drill bits has a shape suitable for ordinary drilling action and, in addition, an internal passageway therethrough for the passage of water or mud. The shanks of the drill bits 32 32,, 32 and 32 are longer than those of drill bits 32 32 and 32f, so that the bit cutting parts of the first mentioned bits project further downwardly than those of the second mentioned. When each drill bit is coupled to its bit drive shaft, the hollow passageways thereof are in mutual communication.

As shown in FIG. 2, a distribution pipe 40, consisting of a combination of several pipe sections, is provided horizontally at the upper part of the main gear casing 34. The distribution pipe 40 is connected to the flexible hose 23 for supplying water and, at the same time, communicates with the passageways 48 48,, 48 and 48 of the bit drive shafts 44,, 44 44 and 44 within the casing sections 34 34,, 34 and 34 respectively.

The passageways 48 within the bit drive shafts 44 are provided at their upper ends with respective constriction sleeves screwed into the shafts 44. Chambers 61 are respectively formed at the upper ends of the casing sections 34 housing the bit drive shafts 44 and are respectively provided at their walls with suitable pipe fittings 62 for the detachable connection thereto of the above mentioned sections of the distribution pipe 40. The pipe fittings 62 which are not in use are closed by screw plugs.

Thus, the water supplied by the flexible water supply hose 23 is passed through the distribution pipe 40, the chambers 61, constriction sleeves 60, the passageways 48 within the bit drive shafts 44,,, 44 44,, and 44 and through their respective drill bits 32. The water is thereby ejected into the holes being drilled by the drill bits 32 32 32 and 32 As shown in FIG. 2, the mud discharge pipes 41 and 41 are connected to the upper ends of the casing sections 34 and 34 and thus communicate with the passageways 48 and 48 within the bit drive shafts 44 and 44 The upper ends of the mud discharge pipes 41 are connected to the inlet end of the discharge hose 24 shown in FIG. 1. Thus, the passageways through the drill bits 32 and 32 and their respective bit drive shafts 44 and 44 are in communication with the mud treatment machine 15. The passageway within the central bit drive shaft 44,, can also be connected to the hose 24 although this connection is not shown.

Shackle fittings 42 are provided on the mud discharge pipes 41 and 41 for fastening the ends of the suspension wire 20.

The central bit drive shaft 44,, is driven by the power produced by the two motors 30 through reduction gears within the reduction gear casing 31 of the organiaztion shown in FIG. 4. A pinion 70 fixed to the output shaft of each motor 30 is in meshing engagement with a gear 72 fixed to a first intermediate shaft 71, and a pinion 73 also fixed to the intermediate shaft 71 is in mesh with a gear 75 fixed to a second intermediate shaft 74. A pinion 76 also fixed to the second intermediate shaft 74 is in mesh with a gear 77 fixed to a central output shaft 78. The lower end of the output shaft 78 is provided with a coupling flange 43 for coupling with the upper end of the central bit drive shaft 44,

The excavation equipment above described operates in the following manner:

First, the frame tower 11 is placed at the position a trench is to be excavated. The excavator is suspended by the suspension wire 20 from the running block 19 and set in the excavating position by the winch 12. Then, by operating the control device 22, the motors 30 of the excavator 10 are started.

The rotational power of the motors 30 is transmitted through the gear train 70, 72, 73, 75, 76, and 77 within the reduction gear casing 31, the shaft 78, and the coupling 43 to the central bit drive shaft 44 within the main gear casing 34. The power is then transmitted from the shaft 44 through the gear train defined by bevel gears 46 and 49 and cross shafts 50 to all of the other bit drive shafts 44 and, therefore, to all drill bits 32, so that the drill bits 32 rotate in the respective directions as described hereinbefore.

By this rotation of the drill bits 32 and by the weight of the excavator 10 imparted downwardly on the bits, the soil is excavated, and a narrow long hole of a length corresponding to the length of the row of drill bits 32 is formed in the ground.

During this excavation, water is supplied to the excavator 10 from the pump 14 through the water supply hose '23. The water passes the distribution pipe 40, through the passageways 48 within the bit drive shafts 44 44 M and 44 and the corresponding drill bits 32 and is ejected against the soil being drilled. The soil thus becomes muddy, thereby facilitating the drilling action of the drills bits.

On one hand, the drill bits 32 32 and 32,, having short shanks and disposed in a row at a position higher than the row of the other drill bits, drill the unexcavated soil parts remaining between the bits of the lower row as they advance behind the lower row. During this operation, the excavated soil in the form of mud is drawn up through the passageways in the bits 32 of the upper row and in their respective drive shafts 44, through the mud discharge pipes 41, and the mud discharge hose 24 by the action of a suction pump or an air lift and is thus transferred to the mud treatment apparatus 15, in which the solid soil is separated from the water.

As described hereinbefore, the direction of rotation of the drill bits 32 and 32 of the upper row are the same, while that of the drill bit 32 is in the opposite direction. Except for the combination of the bits 32,, and 32,,, adjacent bits rotate in mutually opposite directions. During the excavation, this relationship between the bit rotational directions not only aifords stabilization of the bit drilling action but also prevents progressive twisting in the form of the trench as the excavation depth increases. This desirable excavating action is further improved by suspending the excavator 10 by the suspension wir 20.

As the excavation with the bits progresses, the excavator 10 is gradually lowered by unwinding the wire rope 17 on the winch 12 to lower the running block 19. The depth of excavation by the excavator can be readily determined by observing the vertical position of the running block 19.

While twisting of the trench being excavated can be substantially completely prevented by the above described relationship between the bit rotational directions and the suspension of the excavator 10 with the suspension wire 20, it is still possible for some twist to occur in certain cases. When a twist occurs in such cases, it is necessary to stop the excavation operation immediately and to effect appropriate adjustments. Such twists in the trench can be readily detected by a device in accordance with the invention, one example of which is illustrated in FIGS. 5 and 6.

The twist detecting device, generally designated 80, includes a support structure defined essentially by cantilever arm 81 and a mounting bracket 82 for mounting the arm 81 to a suitable structural part of the frame tower 11. A rope follower 83 for encompassing and engaging the wire rope 17 is mounted on the outer end of the arm 81 in a :manner permitting it to slide freely longitudinally of the arm 81. The rope follower 83 has a vertical through hole 84 through which passes one of the two lines or falls of the wire rope 17 between the head sheaves 16 and the running block 19.

The rope follower 83 is fixed on its side facing the root end of the arm 81 to the outer end of a slidable connecting rod 85 slidably supported and guided by a guide member 91 in a direction parallel to the arm 81. The inner end of the connecting rod 85 is provided with a clevis with a pin 86 slidably engaged with a slot 88 in one arm of an angle lever 87 of bell-crank shape rotatably supported by a pivot 89. The other arm of the lever 87 is free and functions as pointer for indicating readings on a calibrated scale 90.

The twist detecting device is mounted on the frame tower 11 to project horizontally such as indicated by the dash line in FIG. 1, in a direction perpendicular to a plane passing through the two parallel lines or falls of the wire rope 17 stretched between the head sheaves 1'6 and the running block 19.

If a twist occurs in the trench being excavated, the excavator 10 will assume a certain angle of askewness relative to the originally desired angular position. This askew angle will then be transmitted through the suspension wire 20 and running block '19 to cause a twist or warp in the plane passing through the two falls of the wire rope 17.

Consequently, the wall of the wire rope passed through the rope follower 83 of the detecting device 80 will un dergo a displacement with a component in the longitudinal direction of the arm 81, whereby the rope follower 83' will undergo a displacement in the longitudinal direction of the arm 81. This displacement will be transmitted through the connecting rod and clevis pin 86 to rotate the angle lever 87, so that the indicator arm of the lever 87 will be displaced along the scale 90 to indicate the direction and magnitude of displacement. From this reading, the direction and magnitude of askewness of the excavator 10 can be determined.

The above described excavation procedure is continued until a trench of the required depth and length determined by the length of the row of drill bits has been formed, whereupon one cycle of excavation has been completed. The excavator 10 is then hoisted clear of the ground, and the frame tower 11 shifted in parallelism in the direction of the trench centerline to a position for excavating a succeeding trench contiguous to and in alignment with the first trench. The cycle of excavation is then repeated. Thereafter, successive cycles of excavation are effected in the same manner to excavate a continuous, long trench.

In certain cases, successive trenches may be formed in an alternately staggered pattern, with each trench having a centerline offset relative to those of the immediately adjacent trenches. The magnitude of this otfset may be of the order of the lateral width of the trench.

As described above, the present invention provides excavation equipment including a novel excavator whereby trenches for underground walls of the desired directions, shapes, and dimensions can be efficiently formed.

What we claim is:

1. Apparatus for excavating trenches for buried walls comprising, in combination: an excavator having an excavator body, water-submersible motive power means installed on the excavator body, and a plurality of drill bits driven [by the motive power means and rotatably supported by the excavator body at the bottom part thereof in one plane adjacent drill bits having partly overlapping drilling paths, approximately one-half of the plurality of drill bits rotating in one rotational direction opposite to that of the remainder of the drill bits, approximately three quarters of the drill bits being provided therethrough with central passageways for water, and the remainder of the drill bits being provided with like passageways for mud; positioning means for lowering and raising the excavator in a suspended state, comprising a hoist structure movably installed on the ground surface, a wire-rope tackle mounted on the hoist structure and including a runniny block, a controllable power driven winch (for operating the wire rope tackle, and a suspension wire device connected at its upper part to said running block and its lower end to the excavator body, and a displacement detecting device mounted on said hoist structure and engaged with said wire-rope tackle for detecting displacement therein due to twist displacement in the suspension wire caused by askewness in the angular position of the excavator body about the vertical axis thereby to detect twist in the shape of the trench being excavated; power supply and control means comprising a control station at the ground level, a waterproof cable connected between the control station and the motive power means of the excavator for controllably supplying power thereto; Water supply means comprising a pump and a hose connecting the pump to said passageways for water through some of the drill bits; and mud removal means comprising a mud discharge hose communicating at its inlet end to all of said passageways for mud through some of the drill bits, and a mud treatment apparatus connected to the outlet end of the mud discharge hose and operating to draw mud through the discharge hose from the region immediately below the excavator body, to separate the mud thus drawn into solid sediments and water, and to return the water thus separated to fill the trench being excavated, with a part of said water being pumped for water supply by the water supply means.

References Cited UNITED STATES PATENTS 305,994 9/1884 Baggsetal 175-391XR 3,324,959 6/1967 Olson "175-108 458,868 9/1891 Van Depoele 175-91 836,494 11/1906 Frieh 6t al. 175-96 861,745 7/1907 Maxwell 37--63 890,764 6/1908 Geare. 2,057,691 10/1936 Ranney 37-195 XR 2,595,126 4/1952 Causey 17596 2,605,090 7/1952 Jacobsen 3763 XR 2,930,137 3/1960 Arps 175- XR FOREIGN PATENTS 591,481 4/1959 Italy. 606,012 6/1960 Italy.

ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, Assistant Examiner US. Cl. X.R. 

